Distributed-aperture strapdown laser seeker and positioning method thereof

Abstract

The present application relates to a kind of distributed aperture strapdown laser seeker and its positioning method, belong to individual guided ammunition and anti-interference technical field.The present application is obtained by distributed light collection aperture acquisition and processing target diffuse reflection signal to obtain coupling signal, by light splitting prism and image rotating prism B, coupling signal is divided into light beam 1 and light beam 2, light beam 1 is directly imaged on photoelectric detector by converging lens, light beam 2 is imaged on photoelectric detector after delay t by wave plate, form TE polarized light and TM polarized light, the peak phase of voltage signal thus generated is different, compare the peak phase and pulse width with the peak phase and pulse width of target signal, use information processor to solve the signal collected, obtain accurate target deviation information, to realize high-precision guidance, the present application can satisfy the premise of easy installation, realize the high-precision guidance of guide head while improving anti-interference ability, meet the requirements of individual guided ammunition intelligent transformation.

Description

Technical Field

[0001] This invention relates to a distributed aperture strapdown laser seeker and its positioning method, belonging to the field of individual soldier guided munitions and anti-jamming technology. Background Technology

[0002] Using low-cost precision-guided munitions to strike high-value enemy targets with pinpoint accuracy is a highly efficient attack method on the modern battlefield. Precision-guided munitions generally employ television, laser semi-active, infrared imaging, and millimeter-wave radar seekers for terminal guidance. The seeker, acting as the missile's "eye," needs to be mounted at the very front of the missile, compressing the space of the warhead. The aforementioned seekers are relatively expensive, accounting for approximately one-tenth of the total missile cost. Man-portable guided munitions have a compact layout and limited warhead space, making them highly cost-sensitive and limiting the development of guided munitions. Current seeker technologies for man-portable guided munitions generally suffer from high cost and large size, and their structural layouts do not meet the requirements of man-portable guided munitions. There is a need to develop a seeker that balances size, weight, accuracy, and cost, with a structural layout that meets the precision guidance requirements of man-portable guided munitions.

[0003] The limiting angular resolution of a semi-active single-aperture optical seeker is primarily influenced by the system's aperture. Improving the system's angular resolution requires increasing the aperture of the optical path. However, limitations in manufacturing processes, payload size and weight, and cost prevent the aperture from being increased indefinitely. Furthermore, single-aperture seekers are susceptible to contamination from munition exhaust plumes. Optical synthetic aperture imaging (OSI) technology can improve seeker imaging resolution while reducing size and manufacturing costs.

[0004] In existing patents for semi-active synthetic aperture imaging guidance, target signal identification utilizes a distributed optical system to receive diffuse reflection signals from the target and converge them into an optical fiber assembly. These signals are then guided by a light guide assembly to a laser acquisition and processing system, where the target deviation angle is calculated. To improve anti-interference capabilities, a narrowband filter with a center wavelength of a first preset wavelength is used to filter out other interference signals. For example, in the prior art patent application number 202210646712.5, entitled "An Anti-interference Distributed Laser Echo Positioner and Target Positioning Method," a four-quadrant detector is used to receive laser echo signals and convert them into electrical signals for output. A front-end circuit processes the electrical signals to obtain four-quadrant voltage amplitudes and transmits the data to the back-end circuit in the form of differential digital signals. The back-end circuit receives the differential digital signals, performs identification and calculation, and obtains the target angle deviation. However, this method has a low recognition rate for light sources with the same wavelength as the target, such as sunlight or interfering light sources, and cannot guarantee high accuracy, posing a risk of interference. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a distributed aperture strapdown laser seeker and its positioning method. This invention can achieve high-precision guidance of the seeker while improving anti-interference capability, under the premise of easy installation, thus meeting the requirements of intelligent transformation of individual soldier guided munitions.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows: a distributed aperture strapdown laser seeker, comprising at least an optical guidance radome and an information processor. The optical seeker radome is provided with four sets of distributed light-collecting assemblies symmetrically arranged relative to the projectile axis. Each set of distributed light-collecting assemblies includes at least a distributed light-collecting aperture, a transmission optical fiber, and an optical transponder assembly. The distributed light-collecting aperture includes at least a receiving objective lens for collecting diffuse reflection signals from the target and an image-spinning prism A. The diffuse reflection signal from the target is compressed at the beam aperture angle by the receiving objective lens, and the signal is adjusted by the image-spinning prism A. After propagation, a coupled optical signal is formed and incident on the optical transponder assembly via the transmission fiber. The optical transponder assembly includes at least a collimating lens, a narrowband filter, a beam splitter, an image-inverting prism B, a waveplate, a polarizer, and a converging lens. The optical signal coupled by the transmission fiber is converted into parallel light by the collimating lens. After passing through the narrowband filter used to filter different wavelength spectral lines, the beam splitter and image-inverting prism B split the filtered optical signal into two beams, beam 1 and beam 2, with the same propagation direction and intensity. Beam 1 is incident on polarizer 1 and then passes through the converging lens to form a beam. The beam 2 is imaged onto the photodetector, thus obtaining a TE polarized wave. After passing through the image-rotating prism B, beam 2 is delayed by time t by a waveplate and then incident on region 2 of polarizer 2, where 0.5T ≤ t ≤ 0.02 / T, where T is the pulse period of the light source in seconds. The beam is then imaged onto the photodetector through a converging lens, thus obtaining a TM polarized wave. The information processor consists of a photodetector, a preamplifier circuit, a signal conditioning circuit, a signal holding circuit, a sampling circuit, and a processor. Each photodetector corresponds one-to-one with a distributed light-gathering component. The four sets of photodetectors respectively... After the light signal collected by the light-collecting component is converted into a voltage signal, it is amplified by a preamplifier circuit. The amplified voltage signal is then conditioned and sampled by a signal conditioning circuit, a signal holding circuit, and a sampling circuit to form a digital signal. The digital signal is then identified and calculated by the recognition program and the sum-difference voltage method running in the processor to obtain the position of the target spot in the field of view, which serves as the carrier guidance and control signal. The field of view observed by the four sets of distributed light-collecting components overlaps at the spring axis. The overlapping area of ​​the field of view is the linear region, and the non-overlapping area of ​​the field of view is the target recognition region.

[0007] The fields of view of the four sets of distributed light-collecting components are evenly distributed on a circle of radius R on a plane tangent to the missile axis, with the missile axis as the center. The four fields of view overlap at the missile axis. The overlapping area of ​​the fields of view is the linear region, and the non-overlapping area of ​​the fields of view is the target recognition region. The angle α between the optical axis of the distributed light-collecting components and the missile axis is 5.5°.

[0008] The polarizers are arranged side by side in polarizer region 1 and polarizer region 2, which are matched with beam 1 and beam 2. Polarizer region 1 is a longitudinal linear grid polarizer used to separate TE polarized waves, and polarizer region 2 is a transverse linear grid polarizer used to separate TM polarized waves.

[0009] The receiving objective lens is coated with an antireflection film that matches the wavelength of the target's reflected signal, in order to improve the transmittance of the target's diffuse reflection signal.

[0010] The transmission fiber uses multimode fiber with an external protective sheath to ensure that the optical signal is converged into the fiber across the entire aperture and field of view.

[0011] The photodetector employs four APD detectors, i.e., avalanche photodiodes, forming four quadrants to receive four sets of optical signals respectively. When the angle between the projectile axis and the optical signal changes, the radiative flux between the four quadrants changes, causing voltage changes in the output of each quadrant. Positioning is achieved through the sum and difference voltages. The four fields of view overlap at the projectile axis. The overlapping area of ​​the fields of view is the linear region with a field of view of ±9°. The non-overlapping area of ​​the fields of view is the target recognition region with fields of view of 9°, 20°, -9°, and -20° respectively. The target recognition region is further subdivided into 12 areas depending on the location.

[0012] It also includes a positioning method for a distributed aperture strapdown laser seeker, the specific steps of which are as follows:

[0013] 1) Target signal processing: The optical signals and background optical signals collected by the four sets of distributed light-collecting components are subjected to time delay and polarization beam splitting processing, and the collected signals are converted into four sets of voltage signals V by a photodetector. a and V b and obtain V a amplitude signal V a ', get V b amplitude signal V b ';

[0014] Select any group of non-zero voltage amplitude signals V a 'and V b'To perform monitoring, starting with the first voltage signal, determine whether the period and pulse width of the voltage signal converted and processed by the photodetector within a fixed time are consistent with the period and pulse width of the target signal, and determine whether the phase delay time of the TM polarized wave is consistent with the target value. If the signals are consistent, proceed to the next step; if the signals are inconsistent, continue monitoring.'

[0015] 2) Calculate the degree of polarization: Extract four sets of voltage signals V respectively. a 'and V b 'Calculate the degree of polarization according to Formula 1:'

[0016] Formula 1

[0017] In the formula: V a 'and V b 'Represents voltage V a and V b The amplitude signal, where P is the obtained degree of polarization;

[0018] The calculated polarization degree P is compared with the polarization degree of the target optical signal. If the difference between the polarization degree P and the polarization degree of the target signal is within the error range, proceed to the next step to determine whether the optical signal is in the target recognition area. If it exceeds the error range, proceed to step 1).

[0019] 3) Target recognition area location determination: Based on different positions in the field of view, the target recognition area is divided into 12 regions, and four voltage amplitude signals V are extracted. a 'and V b The maximum value in ' is denoted as V. A V B V C and V D Based on the magnitude of the four voltage signals, the target's location in the identification zone is determined, and a carrier guidance control signal is sent to drive the projectile to adjust. When the magnitude of all four voltage signals is greater than 0, the next step is directly performed.

[0020] 4) Determination of the location of the linear region: The linear region is located in the overlapping area of ​​the field of view, where V A V B V C and V D All four voltage signals are greater than 0. The angles Δx and Δy between the target beam and the projectile axis in the x-axis and y-axis directions are calculated using formulas 2 to 5:

[0021] Formula 2

[0022] Formula 3

[0023] Formula 4

[0024] Formula 5

[0025] In the formula: m and n are the voltage change ratios calculated by the sum-difference voltage method, a1, b1, and c1 are constants, a1=-5.5527, b1=0.869, and c1=8.258;

[0026] The projectile is driven to make adjustments based on the included angles Δx and Δy as carrier guidance control signals.

[0027] As can be seen from the above technical solution, the distributed aperture strapdown laser seeker and its positioning method provided by the present invention obtain a coupling signal by collecting and processing the target diffuse reflection signal through a distributed light-collecting aperture. The coupling signal is split into beam 1 and beam 2 by a beam splitter and an image-rotating prism B. Beam 1 is directly imaged onto a photodetector through a converging lens, and beam 2 is imaged onto a photodetector after being delayed by t by a waveplate, forming TE polarized light and TM polarized light. The resulting voltage signals have different peak phases. The peak phases and pulse widths are compared with the peak phases and pulse widths of the target signal. The information processor is used to calculate the collected signals to obtain accurate target deviation information, thereby achieving high-precision guidance. The present invention has the following advantages compared with the prior art:

[0028] (1) Because the technical solution adopted in this invention forms two photoelectric signals with different phases through the optical transponder component, namely TE polarized light and TM polarized light, the phase difference of the TM polarized wave will change after being delayed by the waveplate, which can identify whether it is a target signal and separate it from the interference beam. Therefore, this invention can improve the anti-interference capability of the seeker.

[0029] (2) Because the technical solution adopted in this invention collects the diffusely reflected light signals of the target through a distributed light-collecting component, and splits the beam into TE-polarized light and TM-polarized light through a beam splitter and polarizer, and extracts the corresponding voltage signals to calculate the degree of polarization, which can be compared with the degree of polarization of the target beam, this invention can further improve the accuracy of identifying target signals and further improve the anti-interference capability. Extracting polarization information can improve the detection and identification of weak signals under the same background intensity or strong background conditions.

[0030] (3) Because the present invention uses the non-overlapping area of ​​the field of view formed by four sets of distributed light-gathering components as the target recognition area, judges the target position by the corresponding voltage signal, and performs position determination, and uses the overlapping area of ​​the field of view as the linear area, and obtains the spindle angle by calculation, the present invention can achieve high-precision guidance of the guide head more accurately. Attached Figure Description

[0031] Figure 1Schematic diagram of distributed light-gathering component;

[0032] Figure 2 Schematic diagram of the layout of distributed light-gathering components;

[0033] Figure 3 Schematic diagram of the field of view of the distributed light-gathering component;

[0034] Figure 4 Schematic diagram of the optical axis of the distributed light-collecting component;

[0035] Figure 5 Schematic diagram of a polarizer;

[0036] Figure 6 Schematic diagram of an information processor;

[0037] Figure 7 Logic diagram of the sum-difference voltage method;

[0038] Figure 8 Laser seeker positioning logic diagram;

[0039] Figure 9 Schematic diagram of distributed light-gathering aperture.

[0040] In the diagram: 1. Distributed light-gathering assembly; 11. Spindle shaft; 12. Optical axis; 2. Distributed light-gathering aperture; 21. Receiving objective lens; 22. Image-rotating prism A; 3. Optical transponder assembly; 31. Collimating lens; 32. Narrow-band filter; 33. Beam splitter; 34. Image-rotating prism B; 35. Waveplate; 36. Polarizer; 361. Polarizer region 1; 362. Polarizer region 2; 37. Converging lens; 4. Transmission fiber; 41. Transmission fiber end face; 42. Transmission fiber axis; 5. Photodetector. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0042] One example of a distributed aperture strapdown laser seeker provided by this invention is, such as... Figure 1 , Figure 2 and Figure 9 As shown, it includes at least an optical guidance fairing and an information processor. The optical guidance fairing is provided with four sets of distributed light-collecting components 1 symmetrically arranged relative to the missile axis 11. The field of view of the four sets of distributed light-collecting components 1 is centered on the missile axis 11 and is uniformly distributed on a circle of radius R on a plane tangent to the missile axis 11.

[0043] Each set of distributed optical collection components 1 includes at least a distributed optical collection aperture 2, a transmission optical fiber 4, and an optical transponder component 3, such as Figure 8As shown, the distributed light-collecting aperture 2 includes at least a receiving objective lens 21 and an image-rotating prism A22 for collecting the diffuse reflection signal from the target. The diffuse reflection signal from the target is compressed at the beam aperture angle by the receiving objective lens 21, and after the signal propagation angle is adjusted by the image-rotating prism A22, a coupled optical signal is formed and incident on the optical transceiver assembly 3 via the transmission fiber 4. The structure of the distributed light-collecting aperture 2 is as follows: Figure 9 As shown. Figure 9 In the receiving objective lens 21, the first two lenses are used to compress the large field of view on the object side, and the latter two lenses are used to compress the spot size. The image-rotating prism A22 is used to fold the optical path by 90 degrees. (For example...) Figure 4 As shown, the end face 41 of the transmission fiber does not coincide with the focal plane of the receiving objective lens 21, and the relative error between the axis 42 of the transmission fiber and the optical axis 12 is ≤0.12mm. Optical signals are transmitted between the distributed focusing aperture 2 and the optical transponder 3 via optical fiber. To improve coupling efficiency, reduce system loss, and increase the anti-interference probability during target recognition, while considering low cost, a multimode fiber with a numerical aperture of 0.37 and a core diameter of 1mm is selected. To improve the coupling efficiency of the fiber, an anti-reflection coating can also be deposited on the fiber end face. A protective sleeve is added to the transmission fiber 4 to ensure that the optical signal is focused into the fiber across the entire aperture and field of view. The surface of the receiving objective lens 21 is coated with an anti-reflection coating that matches the wavelength of the target reflected signal to improve the transmittance of the target diffuse reflection signal.

[0044] The optical transponder assembly 3 includes at least a collimating lens 31, a narrowband filter 32, a beam splitter 33, an image-inverting prism B34, a waveplate 35, a polarizer 36, and a converging lens 37. The optical signal coupled by the transmission fiber 4 is converted into parallel light by the collimating lens. Due to the special structure of the filter, when light cannot be incident perpendicularly on the filter, the center wavelength of the filter will shift, affecting the amplitude conversion and signal acquisition of the subsequent voltage signal. Therefore, the optical signal coupled by the transmission fiber 4 needs to first be converted into parallel light using the collimating lens before being incident on the narrowband filter 32. After passing through the narrowband filter 32 for filtering different wavelength spectral lines, the filtered optical signal is then split into two beams, beam 1 and beam 2, with the same propagation direction and intensity, by the beam splitter 33 and the image-inverting prism B34. The polarizer 36 has polarizer region 1 361 and polarizer region 2 362 arranged side-by-side to match beam 1 and beam 2, respectively. Figure 5As shown, polarizer 1 region 361 is a longitudinal linear grid polarizer used to separate TE polarized waves, and polarizer 2 region 362 is a transverse linear grid polarizer used to separate TM polarized waves. When beam 1 is incident on polarizer 1 region 361, it is imaged onto photodetector 5 through converging lens 37, thus obtaining a TE polarized wave. Beam 2, after passing through image-rotating prism B34, is delayed by waveplate 35 for a time t before being incident on polarizer 2 region 362, where 0.5T≤t≤0.02 / T, where T is the pulse period of the light source in seconds. It is then imaged onto photodetector 5 through converging lens 37, thus obtaining a TM polarized wave. In this embodiment, the phase of beam 2 and the phase of beam 1 have a phase difference of kπ / 2, where k is an odd or even multiple of π / 2. Waveplate 35 can be a half-wave plate, a full-wave plate, or a λ / 4 waveplate. The converging lens compresses the spot size to the size of the photosensitive surface of photodetector 5. The detector converts beams 1 and 2 into voltage signals. The voltage signals corresponding to TE-polarized and TM-polarized waves have different amplitudes. By reading the amplitudes of these voltages, the degree of polarization can be calculated using a formula. The phase of the TM-polarized wave is delayed by time t compared to the phase of the TE-polarized wave, resulting in different peak phases in the voltage signals. By comparing the peak phase and pulse width with those of the target signal, it can be identified whether it is the target signal, thereby improving the seeker's anti-interference capability.

[0045] The information processor consists of a photodetector 5, a preamplifier circuit, a signal conditioning circuit, a signal holding circuit, a sampling circuit, and a processor, such as... Figure 6 As shown, photodetectors 5 correspond one-to-one with distributed light-collecting components 1. The four sets of photodetectors 5 convert the optical signals collected by the distributed light-collecting components 1 into voltage signals. These voltage signals are then amplified through an amplifier circuit, and further conditioned and sampled by a signal conditioning circuit, a signal holding circuit, and a sampling circuit to form a digital signal. This digital signal is then processed by a recognition program running in the processor, and... Figure 7The sum-difference voltage method shown identifies and calculates the digital signal to obtain the position of the target spot in the field of view, which serves as the carrier guidance control signal. The field of view observed by the four sets of distributed light-collecting components 1 overlaps at the spring axis 11. The overlapping area is the linear region, and the non-overlapping area is the target recognition region. The photodetector 5 uses four APD detectors to form four quadrants to receive the four fields of view respectively. According to the principles of geometric optics, when the light source illuminates the target, a diffuse reflection signal is formed. This signal, relative to the small aperture of the distributed light-collecting aperture 2 with an object distance greater than 50m, can be considered as an infinitely far beam signal. Outside the field of view of the distributed light-collecting aperture 2, the radiant flux illuminating the APD detector is 0, so the current output by the APD detector is 0, and the voltage converted through the transimpedance connected to the APD detector is 0. Within the field of view of the distributed light-collecting aperture 2, the radiant flux illuminating the APD detectors in each quadrant is different, depending on the angle between the target signal and the spring axis 11. When the angle between the projectile shaft 11 and the target signal changes, the radiative flux between the four quadrants changes, causing voltage changes in each quadrant. Positioning is achieved using these voltage differences. The four fields of view overlap at the projectile shaft 11. The overlapping area is the linear region with a field of view of ±9°. The non-overlapping area is the target recognition region with fields of view of 9°, 20°, -9°, and -20°. The target recognition region is further subdivided into 12 areas based on location, such as... Figure 3 As shown.

[0046] Four sets of fields of view overlap at the spring axis 11. The overlapping area of ​​the fields of view is the linear region, and the non-overlapping area is the target recognition region. The angle α between the optical axis 12 of the distributed light-collecting component 1 and the spring axis 11 is 5.5°. In this embodiment, the field of view of the light-collecting component is 29°, and the aperture is 3.2mm. To improve the transmittance of the target wavelength of 1.064μm, and considering the large number of lenses, the transmittance of a single lens of the light-collecting component is >95%, the transmittance of the filter is >80%, the extinction ratio of the polarizer 36 is 1:500, the average reflectance of the waveplate 35 is <1.5%, and the total transmittance of the system is 0.56.

[0047] The photodetector 5 uses four APD detectors to form four quadrants to receive four sets of fields of view. When the angle between the projectile shaft 11 and the target signal changes, the radiative flux between the four quadrants changes, causing the voltage output of each quadrant to change, and the voltage difference is used for positioning. The four sets of fields of view overlap at the projectile shaft 11. The overlapping area of ​​the fields of view is the linear area with a field of view of ±9°. The non-overlapping area of ​​the fields of view is the target recognition area with fields of view of 9°, 20°, -9°, and -20°, respectively. The target recognition area is further subdivided into 12 regions according to different positions.

[0048] It also includes a positioning method for a distributed aperture strapdown laser seeker, the specific steps of which are as follows:

[0049] 1) Target signal processing: The target image is acquired by four sets of distributed light collection components 1. The acquired target diffuse reflection signal and background light signal are delayed and polarized beam splitting processed to convert the collected light signal into four sets of coupled signals to be processed.

[0050] Each set of coupled signals is transmitted through the corresponding transmission fiber 4 to the beam splitter prism 33 and the image inverting prism B34, which splits the coupled signal into two beams, beam 1 and beam 2. Beam 1 is separated into TE polarized waves after passing through polarizer 36, and then illuminates the photodetector 5 to form a voltage V. a and obtain V a amplitude signal V a The beam 2, after being delayed by time t by waveplate 35, passes through polarizer 36 and is separated into a TM polarized wave, which then illuminates photodetector 5 to form a voltage V. b and obtain V b amplitude signal V b ';

[0051] The information processor processes and monitors the voltage signal. Four sets of distributed light-gathering components 1 generate four sets of voltage amplitude signals Va' and Vb'. Considering that at least two of the four sets of voltage amplitude signals Va' and Vb' are not zero within the field of view of the seeker, any set of voltage amplitude signals Va' and Vb' is selected for monitoring. Starting from the first signal, it is determined whether the period and pulse width of the voltage signal converted and processed by the photodetector 5 within a fixed time are consistent with the period and pulse width of the target signal. It is also determined whether the phase delay time of the TM polarization wave is consistent with the target value. If the signals are consistent, the next step is performed. If the signals are inconsistent, monitoring continues.

[0052] 2) Calculate the degree of polarization: Extract the four sets of voltage signals Va' and Vb' respectively, and calculate the degree of polarization according to Formula 1:

[0053] Formula 1

[0054] In the formula: V a 'and V b 'Represents voltage V a and V b The amplitude signal, where P is the obtained degree of polarization;

[0055] The calculated polarization degree P is compared with the polarization degree of the target optical signal. If the difference between the polarization degree P and the polarization degree of the target signal is within the error range, proceed to the next step to determine whether the optical signal is in the target recognition area. If it exceeds the error range, proceed to step 1).

[0056] 3) Target recognition area location determination: Based on different positions within the field of view, the target recognition area is divided into 12 regions, such as... Figure 3 As shown, the target signal is incident on the photosensitive surface of the corresponding detector after passing through a four-way distributed light-collecting component, and is converted into a corresponding voltage signal. After passing through a four-way signal conditioning circuit, signal holding and sampling circuit, it is converted into a corresponding voltage signal amplitude V. a 'and V b In this embodiment, when the target signal light is TE polarized, the amplitude signal V a 'Greater than V b When the target signal light is TM polarized, the amplitude signal V b 'Greater than V a Extract four voltage signals V a 'and V b The maximum amplitude value in ' is denoted as V. A V B V C and V D Based on the magnitudes of the four voltage signals, the target's location within the identification zone is determined, and a carrier guidance control signal is sent to drive the projectile to adjust. When the magnitudes of all four voltage signals are greater than 0, the next step is directly performed. The correspondence between the four voltage signals and the target identification zone in this embodiment is shown in Table 1:

[0057] Table 1. Correspondence between four voltage signals and target recognition areas

[0058] <![CDATA[V A ]]> <![CDATA[V B ]]> <![CDATA[V C ]]> <![CDATA[V D ]]> Corresponding area >0 =0 =0 >0 1 =0 =0 >0 >0 2 =0 =0 =0 >0 3 >0 =0 >0 >0 4 >0 >0 =0 =0 5 =0 >0 >0 =0 6 =0 >0 =0 =0 7 >0 >0 >0 =0 8 >0 =0 =0 =0 9 =0 =0 >0 =0 10 >0 >0 =0 >0 11 =0 >0 >0 >0 13

[0059] like Figure 3 As shown in Table 1, when V A >0, V D >0, V B =0, V C When =0, the target is located in target identification zone 1.

[0060] 4) Determination of the location of the linear region: The linear region is located in the overlapping area of ​​the field of view, where V A V B V C and V D All four voltage signals are greater than 0. The angles Δx and Δy between the target beam and the projectile axis in the x-axis and y-axis directions are calculated using formulas 2 to 5:

[0061] Formula 2

[0062] Formula 3

[0063] Formula 4

[0064] Formula 5

[0065] In the formula: m and n are the voltage change ratios calculated by the sum-difference voltage method, a1, b1, and c1 are constants, a1=-5.5527, b1=0.869, and c1=8.258;

[0066] The projectile is driven to make adjustments based on the included angles Δx and Δy as carrier guidance control signals.

Claims

1. A distributed aperture strapdown laser seeker, comprising at least an optical seeker radome and an information processor, characterized in that: The optical seeker fairing is equipped with four sets of distributed light-collecting assemblies arranged symmetrically with respect to the missile axis. Each set of distributed light-collecting assemblies includes at least a distributed light-collecting aperture, a transmission optical fiber, and an optical transponder assembly. The distributed light-gathering aperture includes at least a receiving objective lens and an image-rotating prism A for collecting the diffuse reflection signal of the target. The diffuse reflection signal of the target is compressed by the receiving objective lens to compress the beam aperture angle, and the signal propagation angle is adjusted by the image-rotating prism A to form a coupled optical signal, which is then incident into the optical transceiver component through the transmission optical fiber. The optical transponder assembly includes at least a collimating lens, a narrowband filter, a beam splitter, an image-splitting prism B, a waveplate, a polarizer, and a converging lens. Optical signals coupled from the transmission fiber are converted into parallel light by the collimating lens. After passing through a narrowband filter used to filter different wavelength spectral lines, the beam splitter and image-splitting prism B further split the filtered optical signal into two beams, beam 1 and beam 2, with the same propagation direction and intensity. Beam 1 is incident on polarizer 1 and imaged onto a photodetector by the converging lens, thus obtaining a TE polarized wave. Beam 2, after passing through image-splitting prism B, is delayed by time t by the waveplate before being incident on polarizer 2, where 0.02T ≤ t ≤ 0.5T, where T is the pulse period of the light source in seconds. It is then imaged onto a photodetector by the converging lens, thus obtaining a TM polarized wave. The information processor consists of photodetectors, a preamplifier circuit, a signal conditioning circuit, a signal holding and sampling circuit, and a processor. The photodetectors correspond one-to-one with the distributed light-collecting components. The four photodetectors convert the light signals collected by the distributed light-collecting components into voltage signals. The voltage signals are then amplified by the preamplifier circuit. The amplified voltage signals are then conditioned and sampled by the signal conditioning circuit, the signal holding and sampling circuit to form digital signals. The digital signals are identified and calculated by the recognition program and the sum and difference voltage method running in the processor to obtain the position of the target light spot in the field of view, which is used as the carrier guidance and control signal. The field of view observed by the four distributed light-collecting components overlaps at the spring axis. The overlapping area of ​​the field of view is the linear region, and the non-overlapping area of ​​the field of view is the target recognition region.

2. The distributed aperture strapdown laser seeker according to claim 1, characterized in that: The fields of view of the four sets of distributed light-collecting components are centered on the missile axis and are evenly distributed on a circle with radius R, with the intersection of the missile axis and the plane perpendicular to the missile axis as the center. The four fields of view overlap at the missile axis. The overlapping area of ​​the fields of view is the linear region, and the non-overlapping area of ​​the fields of view is the target recognition region. The angle α between the optical axis of the distributed light-collecting components and the missile axis is 5.5°.

3. The distributed aperture strapdown laser seeker according to claim 1, characterized in that: The polarizers are arranged side by side in polarizer region 1 and polarizer region 2, which are matched with beam 1 and beam 2. Polarizer region 1 is a longitudinal linear grid polarizer used to separate TE polarized waves, and polarizer region 2 is a transverse linear grid polarizer used to separate TM polarized waves.

4. The distributed aperture strapdown laser seeker according to claim 1, characterized in that: The receiving objective lens is coated with an antireflection film that matches the wavelength of the target diffuse reflection signal, in order to improve the transmittance of the target diffuse reflection signal.

5. The distributed aperture strapdown laser seeker according to claim 1, characterized in that: The transmission fiber uses multimode fiber with an external protective sheath to ensure that the optical signal is converged into the fiber across the entire aperture and field of view.

6. The distributed aperture strapdown laser seeker according to claim 1, characterized in that: The photodetector employs four APD detectors, i.e., avalanche photodiodes, forming four quadrants to receive four sets of optical signals respectively. When the angle between the projectile axis and the optical signal changes, the radiative flux between the four quadrants changes, causing voltage changes in the output of each quadrant. Positioning is achieved through the sum and difference voltages. The four fields of view overlap at the projectile axis. The overlapping area of ​​the fields of view is the linear region with a field of view of ±9°. The non-overlapping area of ​​the fields of view is the target recognition region with fields of view of 9°, 20°, -9°, and -20° respectively. The target recognition region is further subdivided into 12 areas depending on the location.

7. A positioning method for the distributed aperture strapdown laser seeker as described in claim 1, characterized in that... The specific steps are as follows: 1) Target optical signal processing: The optical signals and background optical signals collected by the four sets of distributed light-collecting components are subjected to time delay and polarization beam splitting processing, and the collected signals are converted into four sets of voltage signals V by a photodetector. a and V b and obtain V a amplitude signal V a ', get V b amplitude signal V b '; Select any group of non-zero voltage amplitude signals V a 'and V b 'To perform monitoring, starting with the first voltage signal, determine whether the period and pulse width of the voltage signal converted and processed by the photodetector within a fixed time are consistent with the period and pulse width of the target light signal, and determine whether the phase delay time of the TM polarization wave is consistent with the target value. If the signals are consistent, proceed to the next step; if the signals are inconsistent, continue monitoring.' 2) Calculate the degree of polarization: Extract the four sets of voltage amplitude signals V respectively. a 'and V b 'Calculate the degree of polarization according to Formula 1:' Official 1 In the formula: V a 'and V b 'Represents voltage V a and V b The amplitude signal, where P is the obtained degree of polarization; The calculated polarization degree P is compared with the polarization degree of the target optical signal. If the difference between the polarization degree P and the polarization degree of the target optical signal is within the error range, proceed to the next step to determine whether the optical signal is in the target recognition area. If it exceeds the error range, proceed to step 1). 3) Target recognition area location determination: Based on different positions in the field of view, the target recognition area is divided into 12 regions. The maximum value of four sets of voltage amplitude signals Va' and Vb' is extracted and denoted as V. A V B V C and V D Based on four sets of voltage signals V A V B V C and V D The size of the signal determines the target's location within the identification zone, and a carrier guidance control signal is sent to drive the projectile to adjust; when the four sets of voltage signals V A V B V C and V D If all values ​​are greater than 0, proceed directly to the next step; 4) Determination of the location of the linear region: The linear region is located in the overlapping area of ​​the field of view, where V A V B V C and V D All four voltage signals are greater than 0. The angles Δx and Δy between the target beam and the projectile axis in the x-axis and y-axis directions are calculated using formulas 2 to 5: Official 2 Official 3 Official 4 Official 5 In the formula: m and n are the voltage change ratios calculated by the sum-difference voltage method, a1, b1, and c1 are constants, a1=-5.5527, b1=0.869, and c1=8.258; The projectile is driven to make adjustments based on the included angles Δx and Δy as carrier guidance control signals.

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